The use of dry powder inhalers for the treatment of respiratory diseases such as asthma, COPD, cystic fibrosis, and bronchiectasis is well known.
There are several different types of dry powder inhalers.
One common type is in the form of a disk, which includes an external lever. The lever may be actuated by a user to deposit a dose of medicament into an inhalation chamber, after which it may be inhaled by the user via a mouthpiece.
Another common type of dry powder inhaler is in the form of a generally tube-shaped body, which includes an internal store of a suitable medicament; a rotatable base for dispensing a single dose of the medicament into an appropriate inhalation chamber; and a mouthpiece, through which a user may inhale the medicament that has been dispensed into the inhalation chamber. Such dry powder inhalers usually come with a removable and replaceable screw-cap, adapted to cover the mouthpiece and tube-shaped body of the inhaler, when the inhaler is not in use.
Usually, a single dose of medicament is dispensed into the inhalation chamber when the rotatable base is rotated as far as it will go in one direction, before being returned to its original starting position. This back-and-forth action only needs to be completed once (for dispensing each dose of medicament) and the user should hear a click when this action has been completed successfully.
An example of such a dry powder inhaler is the TURBUHALER® which is manufactured and marketed by AstraZeneca AB.
Another similar type of rotational dry powder inhaler, which also has a generally tube-shaped body, and which also includes an internal store of a suitable medicament, is known as the TWISTHALER®, and is manufactured and marketed by Merck & Co. The TWISTHALER® is similar to the TURBUHALER®, except that the TWISTHALER® dispenses a dose of medicament when the cap is unscrewed from the tube-shaped body. That is, the unscrewing of the cap from the tube-shaped body portion serves to automatically rotate the tube-shaped body with respect to the base portion, and it is this action which dispenses a dose of medicament into the inhalation chamber.
However, for both types of inhaler, a dose of medicament is dispensed into the inhalation chamber when the base portion is rotated with respect to the tube-shaped body, or vice versa.
Usually, the store of medicament is in the form of a single and solid mass, and the rotating of the base portion with respect to the tube-shaped body (or vice versa) causes internal scrapers to scrape a small amount of medicament from off the single mass, after which the removed medicament is directed into the inhalation chamber—in the form of a metered amount of dry powder.
The dry powder is then inhaled by the user by sucking strongly on the mouthpiece.
The internal workings of both types of inhaler are usually configured to create an enhanced internal airflow when the user is sucking on the mouthpiece—which forces the dry powder medicament out through the mouthpiece, and into the mouth of the user, under significant pressure. These internal workings of the inhaler therefore serve to ensure that a maximum amount of the dry powder medicament reaches, and/or is deposited in, the airways and/or lungs of the user.
A problem or difficulty associated with the use of all medicament inhalers (including dry powder inhalers) is poor medicament compliance. Many studies have shown that users frequently do not take their medicament at the predetermined or prescribed times and/or in the required amounts.
The consequences of this non-compliance are reduced disease control, lower quality of life, lost productivity, hospitalisation and avoidable deaths.
In order to address the issue of poor medicament compliance, there are now available a number of compliance monitoring devices for use with medicament inhalers. However, and to date, the majority of these compliance monitoring devices have been designed for use with pressurised metered dose inhalers, rather than dry powder inhalers (due to the greater popularity or availability of pressurised metered dose inhalers).
However, dry powder inhalers have become ever more popular in recent times, and especially those with a tube-shaped body and rotatable base, such as those described previously. And so it is important to be able to utilise compliance monitoring devices with such dry powder inhalers, just as compliance monitoring devices are used with pressurised metered dose inhalers.
A problem associated with the use of all dry powder inhalers is that users sometimes inadvertently forget to remove the cap from the inhaler prior to inhaling their dose of medicament. Moreover, the user may often not realise that he/she has made this mistake and/or may not realise that he/she did not receive the dose of medicament. This will result in the user not receiving their medicament at the designated time, and this may have dire consequences.
Moreover, some health professionals demonstrate use of a dry powder inhaler with the cap on, and so many new users or patients inadvertently copy this erroneous technique, and are unaware that they have not received a dose of medicament.
The ability to record compliance data generally relating as to when the cap is removed and replaced, and/or how many times the user dispenses (or attempts to dispense) a dose of medicament, with the cap still attached to the mouthpiece, would be very useful and important information, both for training purposes or feedback for the user, as well as for general medicament compliance data gathering purposes.
Furthermore, another problem associated with rotational dry powder inhalers such as TURBUHALER®, is that a user may inadvertently only rotate the rotatable base portion once, in one direction. That is, the user does not rotate the base portion back to its starting point—as is required to dispense a dose of medicament on each use. And this incorrect action may be repeated for the next dose. This results in the user not receiving a dose of medicament each time that they thought they had, which is clearly undesirable.
U.S. Pat. No. 8,567,394 (Herder et al) describes a device which locks a dry powder inhaler and prevents the cap being replaced upon the attainment of certain circumstances (for example, if too many doses have been dispensed or if the medicament supply has been exhausted). However, this arrangement is undesirable and/or somewhat meaningless, as the user can then no longer use the inhaler and/or receive their medicament. This would be of particular concern if the user was about to suffer an exacerbation event.
US Patent Publication No. 2004/0187869 (Bjorndal et al) describes a training device for a dry powder inhaler. It includes a closure cap removably positioned over the mouthpiece, and an actuation assembly in the housing for actuating a start switch upon removal of the closure cap. Whilst Bjornal prevents the inhaler from being used with the cap on, it does not allow for compliance data to be gathered relating to how many times the user attempts to use the inhaler with the cap on—and this information would be useful for providing the user with training feedback and/or allowing a health professional to ascertain if the user has inherent difficulties with operation of the inhaler, which need to be addressed. For example, a patient such as a young child or an elderly person or a person with intellectual disabilities is unlikely to be aware of their mistake and/or be able to learn from it without outside intervention or feedback. Furthermore, another disadvantage associated with Bjornal is that if the user is unable to operate the inhaler (namely when the cap is on), they may become confused and/or disinclined to figure out the problem and/or take their required dose of medicament.
US Patent Publication No. 2011/0226242 (Von Hollen et al) describes an inhaler which is adapted to emit an audible instruction (and/or provide audible usage feedback) upon the cap being removed. However, and as for Bjornal, Von Hollen does not allow for compliance data to be gathered relating to how many times the user attempts to use the inhaler with the cap on and/or when, and how often, the cap is removed and/or closed.
U.S. Pat. No. 6,076,521 (Lindahl et al) describes a dose indicating device adapted for use with breath-actuated dry-powder inhalers such as TURBUHALER.® The device is a separate unit which is mounted on a manoeuvring element of the inhalator (i.e. an additional attachment that fits onto the base of the inhaler (See “A” in FIG. 10 of Lindahl). The device comprises a first element constructed to be mounted on and around an outer wall surface of the manoeuvring element and a second element rotatably mounted on and around the outer surface of the first element for rotation relative to the first element. The first and the second elements are connected by a lug/slot mechanism, which allows for a small range of movement of the first and the second elements relative to each other. The relative movement of the elements is necessary to detect a dose delivery. The dose detection means may be mechanical or electronic. While the Lindahl invention offers some advantage over the prior art in the field of DPI compliance monitors, it also has some disadvantages. For example, the device requires an additional manoeuvring element to be added onto the DPI inhaler. Furthermore, while Lindahl states that the device may be attached to the inhaler releasably, it is unclear as to how such a releasable attachment may work. Moreover, the lug/slot system used to put the device together is not user-friendly, especially in the context of the demographics of the target patient population. That is, children, elderly or infirm patients would struggle to operate the lug system.
Another problem associated with the use of TURBUHALER® dry powder inhalers, such as those described previously, is that users, having removed the cap, turn the base of the inhaler only one way at the first use and then the other way at the following use. This results in the user taking the measured dose of medicament only at every other use.
Hence, as well as this skewing the compliance data, it results in the user potentially taking half the prescribed dose of the medicament, which is clearly unsatisfactory.
From a compliance monitoring point of view, with respect to the TURBUHALER®, there is no way of differentiating between when a dose of medicament is dispensed during the normal dispensing of a dose of medicament, as compared to when a dose of medicament is inadvertently dispensed when the cap is being removed and/or replaced.
It may therefore also be of advantage if there was available a compliance monitor for a dry powder medicament inhaler which was able to differentiate between when a user dispenses a dose of medicament normally, as compared to when a dose of medicament is inadvertently dispensed when the cap is being removed or replaced.
Our NZ Patent No. 614928 includes reference to an embodiment of such a compliance monitor, which may be used with a TURBUHALER®.
The compliance monitor described in NZ 614928 is very effective, however one possible drawback or limitation associated with this device is that it lacks the ability to detect and/or record when the compliance monitor has been attached to, and/or removed from, the inhaler—or vice versa.
Another possible drawback associated with the compliance monitor described in NZ 614928 is that the compliance monitor, and associated cap detection means, comprise two portions, and these two portions are screwed together (just as the cap is screwed to the inhaler, as described previously). There are several disadvantages associated with such an arrangement.
Firstly, having to screw the two portions of the compliance monitor together can be a fiddly and/or time consuming process. Moreover, sometimes the two portions may be screwed together with the respective threads not having been lined up properly, resulting in the two portions of the compliance monitor not being properly secured and/or with the compliance monitor not working correctly, or not at all.
Secondly, the action of screwing or unscrewing the two portions of the compliance monitor with respect to each other can sometimes inadvertently rotate the rotatable base of the inhaler at the same time, to thus release (or “half release”) a dose of medicament into the inhalation chamber (just as the action of screwing or unscrewing the cap from the inhaler can do the same—as described previously).
It may be of advantage therefore if there was available a compliance monitor for a dry powder inhaler that can be readily attached to, and/or removed from, the dry powder inhaler without a screw-fit.
The need for a screw-fit is avoided in a compliance monitor for a dry powder inhaler described in U.S. Pat. No. 5,505,195 Wolf et al. Wolf describes a device adapted for mounting on DPIs designed to monitor and record dose release, whether inhalation was proper, and the removal and reattachment of the DPI. The device consists of an electronic housing, which is installed in place of the end cap of the DPI, an activation sheath which slides over the main body of the inhaler and, optionally, a customized sanitary cap. The key disadvantage of Wolf is that in order to connect the device to a DPI the user must take apart and replace parts of the regulated medical device (DPI) and replace them with additional parts. The customization of the original DPI may compromise its functionality and performance. In particular, the fitting of an additional tubular sheath around the device which facilitates the inhalation flow sensing, may affect the performance of the DPI.
It may be of advantage if there was available a user-friendly compliance monitor that was able to be releasably fitted to a DPI without the need for any additional customization of the DPI itself.